(a) Field of the Invention
The present invention relates to a display device and a fabricating method thereof, and more particularly, to a display device and a fabricating method thereof, which can efficiently apply a common voltage across the display and has an improved contrast ratio.
(b) Description of the Related Art
Among flat panel displays, an organic light emitting diode (“OLED”) display has recently attracted attention because it is driven with a low voltage; is both thin and light; has a wide viewing angle; has a relatively short response time; and various other attractive and desirable features. OLED displays are classified as either passive matrix type or an active matrix type according to their respective driving methods.
In the active matrix OLED display, each pixel region is connected to an individual thin film transistor (“TFT”) which controls emission of an organic emission layer in that pixel region. Each pixel region includes a pixel electrode, and each pixel electrode is electrically disconnected from adjacent pixel electrodes so that each pixel can be driven independently. A common electrode is formed on the organic emission layer.
Also, OLED displays are classified into bottom emission type and top emission type according to the direction that light is emitted from the organic emission layer.
In the top emission type OLED display, the light is emitted from the organic emission layer to the outside through the common electrode. Therefore, the top emission type OLED display prevents the loss of aperture ration associated with emitting light to the outside through the TFT. However, in the top emission type OLED display, the common electrode should be transparent. To make the common electrode transparent, the common electrode is formed by thinly depositing metal or by sputtering indium tin oxide (“ITO”) or indium zinc oxide (“IZO”). However, the resistance of the thin common electrode is relatively high, so that it is difficult to apply a common voltage efficiently.